Bacterial vaginosis is a syndrome in which the normal Lactobacillus-predominant vaginal flora is replaced with mixed anaerobic-predominant organisms. It is present in 10 to 25% of women in the general population, and is the most common vaginal infection. It has been associated with a number of adverse sequelae in reproductive health including acquisition of HIV, pelvic inflammatory disease, cervical dysplasia, and complications of gynecological procedures. During pregnancy it has been associated with an increased risk of preterm birth and postpartum maternal infection. However, the vaginal microbial flora remains poorly understood. Information on variation in microbial flora and its association with BV from a longitudinal study is unavailable. This prospective observational study aims to advance our knowledge of the natural history and abnormal alteration in vaginal microbial flora, and to identify risk factors that are associated with these changes. A total of 3600 healthy, non-pregnant women of reproductive age have been enrolled and were followed in Birmingham, Alabama for one year (baseline visit plus once every three months afterwards, totaling five visits). Detailed information on sociodemographic status, medical history, hygiene practice, sexual behavior and psychosocial stress was collected through in-person interviews. Routine gynecological and dental examinations were carried out during the study visits. Samples of vaginal secretion and blood were collected. Laboratory tests to quantify vaginal microbial flora and to identify infection of bacterial vaginosis as well as common sexually transmitted diseases were conducted. Sub-studies evaluate the day-to-day change in vaginal flora, and the effect of cessation of douching.[unreadable] [unreadable] The final study visits were completed in June 2003, and various analyses are underway. In results poublished during this reporting period, a pilot randomized trial of douching cessation and the incidence and persistence of bacterial vaginosis demonstrated the feasibility of such a large trial. Compliance with assigned treatment was very good, and no adverse effects of douching continuation versus cessation were found. Also, perceived psychological stress was demonstrated to increase a woman's risk of acquiring BV. This study used the novel "case-crossover" design, and is the first paper on this topic to utilize this approach. Abstracts describing the association between BV and periodontal disease, between BV and obesity, and on nutritional risk factors for BV were presented. In addition, the case-crossover design on factors that prompt a change in douching behavior resulted in an abstract at this year's Congress of epidemiology. Ongoing analysis are focusing on the effect of douching cessation and BV incidence.[unreadable] [unreadable] In addition, work continued with the NICHD MFMU Network Bacterial Vaginosis and Trichomonas vaginalis clinical trials, publishing several secondary papers from this effort.